191621 has 2 divisors, whose sum is σ = 191622. Its totient is φ = 191620.

The previous prime is 191599. The next prime is 191627. The reversal of 191621 is 126191.

191621 is digitally balanced in base 2, because in such base it contains all the possibile digits an equal number of times.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 98596 + 93025 = 314^2 + 305^2 .

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-191621 is a prime.

It is a Chen prime.

It is a junction number, because it is equal to n+sod(n) for n = 191593 and 191602.

It is a congruent number.

It is an inconsummate number, since it does not exist a number n which divided by its sum of digits gives 191621.

It is not a weakly prime, because it can be changed into another prime (191627) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 95810 + 95811.

It is an arithmetic number, because the mean of its divisors is an integer number (95811).

2¹⁹¹⁶²¹ is an apocalyptic number.

It is an amenable number.

191621 is a deficient number, since it is larger than the sum of its proper divisors (1).

191621 is an equidigital number, since it uses as much as digits as its factorization.

191621 is an odious number, because the sum of its binary digits is odd.

The product of its digits is 108, while the sum is 20.

The square root of 191621 is about 437.7453597698. The cubic root of 191621 is about 57.6519986008.

The spelling of 191621 in words is "one hundred ninety-one thousand, six hundred twenty-one".